TY: THES
T1 - Lentiviral target-specific strategy for molecular therapy
A1 - Fonseca, Lídia Maria dos Santos, 1977-
N2 - A crucial factor for successful gene therapy is the efficacy of specific gene transfer, which is usually done by lentiviral vectors. Binding specificity and fusion of lentiviral vectors must be provided by envelope glycoprotein domains. The Sindbis virus envelope can pseudotype lentiviral particles and display exogenous protein domains. Previous results from this lab demonstrated that Sindbis envelope can accommodate anti-receptor single-chain antibodies (scFv) and target via cell-specific viral infection. In addition, Dr Irvin Chen laboratory has shown that Protein A-chimeric Sindbis envelope can specifically target cells immunolabelled with anti-receptor IgG via Fc recognition. However, these strategies might present some problems for in vivo applications, since there may be non-specific reactions with plasma antibodies and the need for cloning a receptor specific antibody each time a new molecule needs to be targeted. To overcome these problems we developed a new lentiviral vector capable of transducing several cell types in a specific manner without the above constraints, that consists of a chimeric scFv-Sindbis virus envelope that binds fluorescein isothiocyanate (FITC) with high affinity and consequently recognize FITC-conjugated proteins. Therefore, a target cell expressing on its surface a receptor targeted by FITCconjugated IgG can be infected by this scFv-Sindbis envelope pseudotyped lentiviral vector. Anti-FITC scFv was successfully incorporated at the surface of Sindbispseudotyped lentiviruses and could bind to FITC-labelled cells. Using this targeting strategy, we were able, in vitro, to target efficiently and specifically Jurkat cells labelled by a CD7 FITC-conjugated antibody. Moreover, we could specifically kill those transduced cells using an HSV-TK/GCV suicide gene strategy. The in vivo efficiency of this gene therapy proposal was tested in a mouse model of T-cell acute lymphoblastic leukaemia (T-ALL), which allowed targeting 15.2% of the tumour cells. This provides an alternative strategy to deliver molecular therapeutics using a modular specific targeting with lentiviruses. Moreover, it will overcome the need for new scFv cloning each time a new cell receptor must be targeted and it will avoid the competition by serum antibodies when applied in vivo, since the chimeric envelope will only recognize an organic molecule not present in the serum. Although the Lentiviral target-specific strategy for molecular therapy vi strategy herein proposed was applied to a leukaemia model it has the potential to be applied to a broad range of diseases.
UR - http://repositorio.ul.pt/handle/10451/5765
Y1 - 2012
PB - No publisher defined